Driving mechanism for recorder pens or the like



Dc. 10, 1957 5 STRIMEL 2,815,675

DRIVING MECHANISM FOR RECORDER PENS OR THE LIKE Original Filed June 11.1951 2 shaetysheet 1 INVENTOR M 1M4 WWW,

A 770! NE YJ Dec. 10, 1957 R. s. STRIMEL 2,815,675

DRIVING MECHANISM FOR RECORDER PENS OR THE LIKE Original Filed June 11,1951 2 Sheets-Sheet 2 m/EumK MHW A TfoRNE v5 2,815,675 Patented Dec. 10,1957 DRIVING MECHANISM FOR RECORDER PEN S OR THE LIKE Robert S. Strimel,Conshohocken, Pa., assignor to Tinius Olsen Testing Machine Company,Willow Grove, Pa., a corporation of Pennsylvania Original applicationJune 11, 1951, Serial No. 230,877,

now Patent No. 2,808,721, dated October 8, 1957. Divided and thisapplication April 27, 1954, Serial No. 425,829

6 Claims. (Cl. 74-422) This invention relates generally to drum-pen typerecorders for use with testing machines and, in particular, relates todrive mechanism for the pen of such a recorder.

The subject matter of the invention is fully described in my copendingapplication, Serial No. 230,877, filed June 11, 1951, now Patent No.2,808,721, and entitled 21 Registering System for Use in ConjunctionWith Testing Machines, of which this application is a division.

My copending application discloses a testing machine comprising anupright housing having a scale and a pointer to be observed by theoperator making tests. The pointer is driven in accordance with the loador stress applied to an article being tested, for example, tests incompression, fierure or tension. On one side of the housing is disposeda drum-pen type recorder which may be used for the recording ofstress-strain curves, the drum being driven in accordance with strainand the pen being driven in accordance with stress. As pointed out inthat application, it is highly desirable, in making such stress-straincurves, to provide for magnification of the recording to enable detailedstudy of specimen behavior.

The present invention concerns mechanism actuable by the indicatingpointer driving system which moves the recorder pen and also providesfor magnification of the stress record made by the pen.

The invention contemplates mechanism disposed within the housing of atesting machine comprising a rod mounted both for translational androtational movement, one end of the rod projecting outside of thehousing and carrying a pen to be moved 'over the drum of the recorder.The rod is disposed interjacent two gears, one small and one large,which preferably are directly attached to the drive shaft of the testingmachine pointer. A rack having sets of teeth on two opposing faces issecured to the rod such that when the rod is rotated in one direction,one set of teeth engages the large gear and when rotated in the oppositedirection, the other set of teeth engages the small gear.

Any given movement of the pointer shaft produces identical angularmovements of the two gears. However, since the gears are of differentdiameter, corresponding peripheral points move different lineardistances. Thus, with the rack engaging the small gear, the pen will bemoved a given linear distance per angular movement of the gears and whenthe rack engages the large gear, a greater corresponding linear movementwill be imparted to the rack. A knob is provided on one end of the gearto provide for selective engagement of the rack with one or the other ofthe gears. Thus, by the operator merely turning the knob, magnificationof the recording may be easily effected.

The invention also contemplates means for preventing over-travel of thepen. This takes the form of certain cams or abutments which are disposedalong the path of movement of the rod and operate to break theengagement of the rack with either gear and accordingly, stop movementof the pen.

The manner in which the foregoing is accomplished will be apparent fromthe following description and drawings wherein:

Figure 1 is an elevational view of certain parts of the mechanism of theinvention;

Figure 2 is an enlarged elevational view of the mechanism of Figure 1looking from the right-hand side;

Figure 3 is a fragmentary view showing the rack engaging an abutmentwhereby the connection between the rack and the large gear is broken;

Figure 4 is a fragmentary view showing the rack engaged with the smallergear; and

Figure 5 is a fragmentary view showing a portion of a testing machineand a portion of a recorder together with the recorder pen attached tothe rod.

Figure 5 shows a portion of a housing H of a testing machine having acalibrated scale S over which a pointer P is adapted to be moved.Secured on the side of the housing is a recorder R having a rotatabledrum D and a pen P. The pen is secured to a rod R which is adapted tomove the pen back and forth over the surface of the drum. Thedescription which follows concerns the mechanism for driving the rod,hence the pen, over the surface of the drum.

In Figure 2 a plate 1 is adapted to be secured within the housing H. Amounting plate 2 carrying certain mechanism which will be mentionedlater, is connected with the plate 1 by mounting studs 4-4. Anothermounting plate 5 is secured to the mounting plate 2 by the mountingstuds 66. The mounting plate 5 carries a servo motor 7, the manner inwhich the servo motor is operated being described in my copendingapplication. Bearings 8 and 9 respectively mounted in plates 2 and 5,carry the indicating pointer drive shaft 10, the shaft being connectedwith and adapted to rotate a pointer such as indicated by the letter Pin Figure 5. A gear 11 is secured to the drive shaft 10 and this gearmeshes with a pinion 12 rotated by the servo motor 7. Thus, it will beapparent that rotation of the motor rotates the pointer drive shaft, therotation being either clockwise or counterclockwise. The gear 11 isprovided with a pin 13, which is adapted to engage a stop 14 on theplate 5 when the pointer shaft moves greater than a predeterminedangular distance. This is to prevent over-travel of the pointer at thehigh end of the scale.

Also secured to pointer shaft 10 in spaced apart relationship are gears15 and 16. As will be apparent, the gear 16 has a greater diameter thangear 15. In the preferred embodiment, the diameter of gear 16 is twicethe diameter of gear 15 such that for the same angular movement of thegears, the ratio of linear movement of two corresponding peripheralpoints is 2: 1.

A cam 17 and an operating arm 18 are also carried by pointer shaft 10.The cam operates cam follower mechanism generally indicated by 19, whichactuates certain transducer mechanism generally indicated by 20. Theoperating arm 18 is adapted to actuate certain switch mechanismgenerally indicated by 21, to prevent overtravel of the pointer attachedto the shaft 10. The functioning of the cam and transducer, the arm andthe switch are fully described in my copending application and need notbe mentioned further here.

As seen in Figures 1 and 2, a mounting bar 22 is secured to plate 1. Themounting bar carries bearings 23 and 24, which support the rod R suchthat the rod may be moved in translation or may be rotated. The end ofthe rod designated by the numeral 26 is adapted to project through thehousing H of the testing machine as indicated in Figure 5. The end 26carries the pen P. The pen is secured on the rod by an adapter 27incorporating frictional means such that the rod and the pen movetogether but permitting rotation of the rod relative to the adapter. Atthe outer end of the rod is a knob 28, by means of which the rod may berotated.

A rack 29 having on opposing faces thereof teeth 30 and 31, is fixedlysecured to the rod by means of right angle members 32 and 33. As will beseen from an inspection of Figures 2 and 4, when the rod is rotated inthe clockwise direction (as viewed in Figure 2), the teeth 31 of therack engage the large gear 16, and when the rod is rotated in thecounter-clockwise direction, the teeth 30 of the rack engage the smallgear 15, as shown in Figure 4.

It will be apparent that the selective engagement of the rack with gearsof different diameter can change the ratio of movement of the pin withrespect to the movement of the pointer or pointer shaft. Thus, thearrangement provides for magnification of the stress recording made bythe pen. This is important because it enables a highly detailed study ofspecimen behavior in any portion of the stress range. For example, it isoften desirable in test work to observe the action of the specimen inthe early plastic stages. Thus, a test specimen may be loaded, say, upto or near the elastic limit with the rack engaged with gear 15. Thenthe knob 28 may be turned to engage the rack with gear 16. Upon furtherapplication of stress, the recording will be magnified, thus providingfor a detailed study of the specimen in the plastic stages.

The invention contemplates certain safety features which preventover-travel of the recorder pen. This is accomplished by cam surfacesassociated with the rack 29. With reference to Figure 1, it will beobserved that the rack has V-shaped sections 34 and 35. As the rackmoves toward the right-hand side, the V-shaped section 34 will engage apin or cam 36, which tends to rock or rotate the rack out of engagementwith the gear 16, this action being clearly shown in Figure 3. When therack is moved toward the left-hand side, the V-shaped section 35contacts the pin 37 and rotates the rack out of engagement. When therack is engaged with gear 15, the pins 38 and 39 operate in a mannerdescribed above.

It will also be apparent that the pen may be rendered inoperative by thetwisting of knob 28 to disengage the rack from the gear and then movingthe rod such that the rack engages one of the cams and rests thereon.

While I have described the invention in connection with recorder pens,it will be apparent that the invention may be applied in otherarrangements, for example, when the rod is driven by a prime mover andthe two gears connected to a mechanism to be driven.

Iclaim:

1. For use with a recorder for recording information, said recorderhaving a drum and a pen, a drive mechanism for the pen comprising: a rodconnected with the pen and adapted to be rotated and to be driven intranslation; a plurality of gears each of different diameter, eachadapted to be rotated in accordance with information to be recorded;means connected with the rod and rotatable therewith to provide fordriving interconnection of the rod alternatively with any of said gears;and cam means disposed along the path of movement of the rod and adaptedto be contacted by last said means whereby to disengage said drivinginterconnection.

2. A drive system comprising in combination: two gears each of differentdiameter and mounted in spaced apart planes generally parallel to oneanother; a rod disposed intermediate said gears and mounted for bothrotational and translational movement in a plane generally parallel tothe planes of said gears; and a rack having sets of teeth respectivelyon opposing faces thereof mounted on said rod and arranged wherebyrotation of the rod in one direction engages one set of teeth of therack with one gear and rotation of the rod in the opposite directionengages the other set of teeth of the rack with the other gear.

3. For use with a recorder for recording information, said recorderhaving a drum and a pen, a system for driving the pen comprising: tworotatable driven gears each of ditferent diameter mounted on commondrive means; a rotatable rod connected with said pen and adapted to bedriven in translation by either of said gears; and a rack connected withthe rod and adapted upon rotation of the rod to be selectively engagedwith either of said gears whereby the rod is moved in translation inaccordance with the movement of the engaged gear.

4. A construction in accordance with claim 4 further including cam meansdisposed along the path of movement of said rod and adapted to engagesaid rack when being driven by either of said gears whereby to move therack out of said engagement.

5. A construction in accordance with claim 5 wherein said rack has aV-shaped section at each end thereof and said cam means comprises twopairs of pins.

6. For use with a recorder for recording information, said recorderhaving a drum and a pen, a drive mechanism for the pen comprising: a rodconnected with the pen and adapted to be rotated and to be driven intranslation; a plurality of gears each of different diameter, eachadapted to be rotated in accordance with information to be recorded; andmeans connected with the rod and rotatable therewith to provide fordriving interconnection of the rod alternatively with any of said gears.

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